1. Field of the Invention
The invention relates to an active matrix type display device and portable machine comprising the same.
2. Description of the Related Art
Liquid crystal displays (LCDs) utilize voltage to vary alignment of liquid crystal molecules, and can display images, wherein environmental light or backlight is allowed to pass through or be shielded. Presently, the typical types of LCDs comprise the transmissive type, utilizing backlight modules on the back surface of a screen to display images, the reflective type, reflecting environmental light to display images without backlight modules, and the transflective type, utilizing environmental light reflection and backlight modules.
For the above mentioned LCDs, the reflective type LCD display is the most popular utilized in machines, capable of hand carry, driven by batteries because power consumption is low due to absence of backlight modules. These machines comprise portable machines such as mobile phones and personal digital assistants (PDAs), etc. Mobile phones, for example, are mainly in a standby state when used, and usually display still images in all or most of the display part at that time. Alternatively, mobile phones also usually use low bit color functional displays like a clock display.
For conventional reflective type display devices, data is written into pixels by drivers in the same manner in either of moving pictures displaying mode and still pictures displaying mode. In this situation, typically, the same data are written into the pixels when displaying still pictures. Thus, a technology (refer to patent document 1 JP2007-328351, for example) is proposed to stop driving the driver and decrease power consumption due to disposing memories in every pixel and writing memorized data in the memories into the pixels when displaying still pictures. The technology is typically known as the MIP (memory in pixel) technology.
Further, multi-bit MIP technology has also been disclosed, achieving multi gradation display for displaying of still pictures, wherein one pixel is divided into a plurality of sub-pixels, memories are disposed in each sub-pixel, and digital data with bit numbers corresponding the sub-pixel numbers is input to the pixel (refer to patent document 2 JP2005-148425, for example).